This invention relates to optional printing and typesetting machinery for ideographic writing systems. It is characteristic of such systems that they require a very large vocabulary of graphically distinct items and the provision of automatic machinery to handle such large vocabularies represents a considerable technical problem. In the case of the Chinese language, which will be used as an example in the present specification, the very minimum vocabulary is above 2,000 items, while a total repertoire of some 40,000 items, some of which are admittelly of very rare occurence, could be achieved. A rotary stroboscopic printer for 5,000 characters has been proposed, but complicated justifying arrangements are needed to correct the position of characters lying in different circular bands on the rotating disc, and the output is limited as to type face. Alternative techniques involve computer storage of drawing specifications for a set of Chinese characters, but this requires large quantities of digital storage for even a single very primitive style of character.
A relatively recent development in information storage has been the use of holograms, in which information is stored in the form of optical diffraction patterns. A few tentative proposals have been made in the direction of storing alphanumeric symbols in this way and reconstructing them by illumination with monochromatic radiation, for example laser illumination. However, the arrangements proposed have not been suitable either for handling very large vocabularies, such as are required for ideographic scripts, or for providing the necessary degree of resolution for typesetting work.